Abstract
Slow component of oxygen uptake (VO2SC) kinetics and maximal oxygen uptake (VO2max) attainment seem to influence endurance performance during constant-work rate exercise (CWR) performed within the severe intensity domain. In this study, it was hypothesized that delaying the attainment of VO2max by reducing the rates at which VO2 increases with time (VO2SC kinetics) would improve the endurance performance during severe-intensity intermittent exercise performed with different work:recovery duration and recovery type in active individuals. After the estimation of the parameters of the VO2SC kinetics during CWR exercise, 18 males were divided into two groups (Passive and Active recovery) and performed at different days, two intermittent exercises to exhaustion (at 95% IVO2max, with work: recovery ratio of 2:1) with the duration of the repetitions calculated from the onset of the exercise to the beginning of the VO2SC (Short) or to the half duration of the VO2SC (Long). The active recovery was performed at 50% IVO2max. The endurance performance during intermittent exercises for the Passive (Short = 1523 ± 411; Long = 984 ± 260 s) and Active (Short = 902 ± 239; Long = 886 ± 254 s) groups was improved compared with CWR condition (Passive = 540 ± 116; Active = 489 ± 84 s). For Passive group, the endurance performance was significantly higher for Short than Long condition. However, no significant difference between Short and Long conditions was found for Active group. Additionally, the endurance performance during Short condition was higher for Passive than Active group. The VO2SC kinetics was significantly increased for CWR (Passive = 0.16 ± 0.04; Active = 0.16 ± 0.04 L.min−2) compared with Short (Passive = 0.01 ± 0.01; Active = 0.03 ± 0.04 L.min−2) and Long (Passive = 0.02 ± 0.01; Active = 0.01 ± 0.01 L.min−2) intermittent exercise conditions. No significant difference was found among the intermittent exercises. It can be concluded that the endurance performance is negatively influenced by active recovery only during shorter high-intensity intermittent exercise. Moreover, the improvement in endurance performance seems not be explained by differences in the VO2SC kinetics, since its values were similar among all intermittent exercise conditions.
Highlights
The parameters of the power-time relationship, termed critical power (CP) and the curvature constant (W’), have been used to analyze the physiological responses and endurance performance during high-intensity exercise (Poole et al, 1988)
Based on the VO2 kinetics parameters obtained during constant-work rate exercise (CWR), the repetition duration for the Short (PR = 105 ± 29 s; active recovery (AR) = 132 ± 39 s) and Long (PR = 252 ± 50 s; AR = 253 ± 56 s) tests were not significantly different between the groups (p > 0.05)
The present study showed that under our experimental conditions, intermittent exercise enhances endurance performance during severe-intensity exercise, independently of intervals duration and recovery type
Summary
The parameters of the power-time relationship, termed critical power (CP) and the curvature constant (W’), have been used to analyze the physiological responses and endurance performance during high-intensity exercise (Poole et al, 1988). CP has been considered the lower boundary of the severe-intensity domain and the W’ determines the amount of external work that can be performed above CP, irrespective of the rate of its expenditure (Jones et al, 2010). All severe-intensity work rates (i.e., >CP) performed until voluntary exhaustion drive pulmonary oxygen uptake (VO2) to a maximal value (i.e., maximal oxygen uptake—VO2max) (Jones et al, 2010). During exhaustive exercise performed above the upper bound of the severe intensity domain, exercise duration would be too short to permit attainment of VO2max Caputo and Denadai (2008). Several studies have demonstrated that endurance exercise performance within severe-intensity domain was coincident with the depletion of the W’, accumulation of metabolites associated with fatigue (i.e., PCr, Pi, and H+), and attainment of VO2max due to VO2 slow component (VO2SC) development (Fukuba et al, 2003; Chidnok et al, 2013). VO2SC has been associated with loss in muscular efficiency (Jones et al, 2011) and has been negatively related with endurance performance (Zoladz et al, 1995; Murgatroyd et al, 2011; Barbosa et al, 2014a)
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